New research reveals how cat dander triggers allergic responses

New research reveals how the most common cause of severe allergic reactions to cats, the Fel d 1 protein which is found in cat dander, triggers an allergic response.

Scientists have discovered that when the cat protein Fel d 1 is in the presence of very low doses of the ubiquitous environmental , lipopolysaccharide (LPS), it activates the pathogen recognition receptor Toll-like receptor 4. Until now, it was not understood how Fel d 1 generated such a large inflammatory response in the immune system.

Allergic reactions are the result of the immune system overreacting to a perceived danger. Instead of identifying and responding to a harmful virus or bacteria, it misidentifies different allergens, including dander (microscopic pieces of often accompanied by dried saliva from grooming), as dangerous and mounts an .

In order to find out how Fel d 1 triggers these , the researchers exposed human cells to cat and dog dander proteins in the presence or absence of low levels of LPS. The researchers found that when the bacterial toxin LPS is present, it increases the signalling to the body's immune system, intensifying the body's inflammatory response to the cat protein Fel d 1.

They also discovered that the part of the immune system that recognises the LPS contaminated Fel d 1 is the pathogen recognition receptor Toll-like receptor 4 (TLR4). (TLR4 also plays a role in a heightened immune response, and subsequent allergic reaction, to dust mite allergens and as well as the metal nickel.) The researchers then used a drug which inhibits the TLR4 response and found that it blocks the effects of the cat dander protein on , thereby preventing an .

Dr Clare Bryant, lead author of the research from the University of Cambridge's Department of Veterinary Medicine, said: "How cat dander causes such a severe allergic reaction in some people has long been a mystery. Not only did we find out that LPS exacerbates the immune response's reaction to cat dander, we identified the part of immune system that recognises it, the receptor TLR4."

Additional research revealed that the dog allergen Can f 6 (a protein found in dog dander) also enhances LPS-induced activation of TLR4. The researchers believe that dog-allergy sufferers could also benefit from new drugs which inhibit TLR4.

Dr Bryant continued: "As drugs have already been developed to inhibit the receptor TLR4, we are hopeful that our research will lead to new and improved treatments for cat and possibly dog allergy sufferers."

The research was funded by the Wellcome Trust and the Medical Research Council (MRC). It was published in the The Journal of Immunology.

add to favorites email to friend print save as pdf

Related Stories

Cell component involved in triggering cat allergy

Mar 08, 2011

(PhysOrg.com) -- A breakthrough by scientists at The University of Nottingham could provide hope for any allergy sufferers who have ever had to choose between their health and their household pet.

A new cat in adulthood can up your allergy risk

Dec 28, 2011

(Medical Xpress) -- According to a new study published in The Journal of Allergy and Clinical Immunology, getting a cat for the first time as an adult can nearly double your chances of developing allergies to the ...

Recommended for you

Radical vaccine design effective against herpes viruses

5 hours ago

Herpes simplex virus infections are an enormous global health problem and there is currently no viable vaccine. For nearly three decades, immunologists' efforts to develop a herpes vaccine have centered on ...

Popular antioxidant likely ineffective, study finds

14 hours ago

The popular dietary supplement ubiquinone, also known as Coenzyme Q10, is widely believed to function as an antioxidant, protecting cells against damage from free radicals. But a new study by scientists at McGill University ...

New findings on 'key players' in brain inflammation

14 hours ago

Inflammation is the immune system's natural reaction to an 'aggressor' in the body or an injury, but if the inflammatory response is too strong it becomes harmful. For example, inflammation in the brain occurs ...

Gut microbial mix relates to stages of blood sugar control

Mar 05, 2015

The composition of intestinal bacteria and other micro-organisms—called the gut microbiota—changes over time in unhealthy ways in black men who are prediabetic, a new study finds. The results will be presented Friday ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.